A couple of UMass profs and an outside pollster have co-authored a paper in which they find evidence that racism and sexism were factors in Trump's win, along with economic concerns. Vox has an article which, unsurprisingly, makes much of this finding.
I am inclined to believe this is probably true to some extent. Democrats spent eight years telling white Americans they are evil, vicious, and irredeemably biased and hooked on "white privilege." And telling white males they are also sexist pigs.
Do you suppose most white Americans replied "sure, that's me, I'm an evil slug"? Or do you think it more likely most whites said, to themselves if not to others, "not only hell no, but I really resent you for saying so,"
That's the trouble with identity group politics, you cozy up to one group by agreeing with them that they're victimized by another group. Your problem, the other group is listening and sees you taking sides against them.
In other words, identity group politics emphasizes what differentiates groups instead of what they have in common. It is disingenuous for Democrats to claim surprise when, mirable dictu, intergroup hostility grows worse. Democrats fostered it, and cannot now disavow it.
Talk about sowing the wind and reaping the whirlwind ... 2016 was that year for Democrats.